The purpose of this clinical trial is to evaluate and compare the outcomes of selective carious tissue removal versus stepwise carious tissue removal in young permanent teeth with deep carious lesions. The primary follow-up will be conducted 1 year after treatment to assess success. A secondary follow-up will take place 3 years post-treatment, utilizing data from dental registries and dental records. The study is a randomized controlled trial conducted within a practice-based research network.

The SELECT compares selective carious tissue removal and stepwise excavation in young permanent teeth with deep carious lesions. Unlike the traditional approach of total caries excavation-still widely practiced by dentists-the study implements minimally invasive methods in clinical settings. Conducted within a practice-based research network (PBRN), the study ensures that its findings are highly relevant to real-world clinical environments. Targeting young permanent teeth, a population critical for long-term dental health, the study has a robust randomized controlled trial (RCT) design. Its long follow-up period includes a clinical assessments at 1 year, and at 3 years using dental registry data/dental records. The focus on minimally invasive techniques aligns with contemporary trends in conservative dentistry, and the findings have the potential to inform future guidelines, advancing evidence-based and sustainable treatment practices.

Aim: The aim of the SELECT study is to compare the clinical and long-term outcomes of selective carious tissue removal versus stepwise excavation in managing deep carious lesions in young permanent teeth. The study aims to determine which method is more effective in preserving tooth vitality, reducing complications, and supporting sustainable dental health. The implementation of minimally invasive methods in routine dental practice is a key component of this study, emphasizing the importance of patient-centered and less invasive care.

Selection of participants: Participants will be recruited through the PBRN and all eligible patients will be considered if they comply with the clearly defined inclusion and exclusion criteria.

Statistical plan and data analysis: The sample size calculations is based on the statistical power to reject the null hypothesis H0" No difference between treatment types" at a 5% risk level of type I error. The sample size for each treatment group is determined to be 333 participants based on the primary outcome, with a primary follow-up period of 1 to 1,5 year including an attrition rate of 20%. The success probability for stepwise excavation is set at 90%, with a risk difference of +6 percentage points for selective excavation. The study is powered with a type-I error of 5% and a type-II error of 20%. For the follow-up data after 2-3 years, a base success probability of 80% for stepwise excavation was assumed and a risk difference of +10% for selective excavation rending for a sample size of 392 patients. The outcome will be a vital tooth without pain as a binary variable indicating a successful or unsuccessful treatment and a logistic regression analysis will be performed.

Randomization: Only one deep caries lesion per participant will be randomized. The trial will use block randomization.

Blinding: Blinding of the dental team performing the dental treatment or the patient is not possible as there is a one-visit or a two-visit procedure. The statistical analyses will be performed blinded.

Discontinuation and withdrawal: If a patient does not show up for an examination or treatment an effort will be made to reschedule for the visit and finding the reason for not showing up. But the participation is on a voluntary basis and the participant can chose to leave the study at any time. To facilitate the follow-up examination, there is some flexibility in the follow up period. If the patient fail to attend the scheduled appointment, at least one more appointment will be offered and preceded with a phone-call. Loss of follow up has been accounted for in the calculation of sample size

Inclusion Criteria:

Children aged 8- 19 years (last December the year they turn 19 years) A fully erupted molar or pre-molar teeth with dental caries (class I or class II) extending to more than 2/3 of the dentine thickness (and on the bitewing radiograph showing a radiodense zone separating the pulp from the demineralized dentine).

Bitewing radiograph has been taken as part of the ordinary dental examination Available for recall at least for 1 year.

Exclusion Criteria:

Extraction is planned of the tooth with deep caries in the future with expected spontaneous gap closure.

If the carious tooth shows sign or symptoms of irreversible pulp pathology or loss of vitality including:

• Presence of a sinus tract (fistula)
• Tenderness to percussion
• Buccal tenderness
• Severe sensitivity
• Evidence of pathology on a periapical radiograph (if radiograph is clinically justified and performed)
• No written informed consent.
• Medical condition requiring special considerations with regard of the dental management
• Dental treatment cannot be performed adequate due to lack cooperation

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